1. Technical Field
The present invention relates to an electrophoretic device driving method, an electrophoretic device, and an electronic apparatus and an electronic watch that include the electrophoretic device.
2. Related Art
A phenomenon (electrophoretic phenomenon) is known in which the application of an electric field to a dispersed system including electrophoretic particles dispersed in a solution causes the electrophoretic particles to migrate due to the Coulomb force. Electrophoretic display devices utilizing such a phenomenon have been developed.
In such electrophoretic display devices, when a display state is maintained for a long period of time, electrophoretic particles may become adhered to an electrode or the like. Thus, the particles may move slowly when rewriting is performed, and a residual image may be generated. For example, when an electrophoretic display device is used for an electronic watch, a plurality of units of display, such as a month display, a date display, an hour display, a minute display, and a second display, are provided in a display region. Such units of display have greatly different rewrite intervals. For the month display and the date display, the same display is maintained for a long period of time. More specifically, for the month display, the same display is maintained for about 720 hours. For the date display, the same display is maintained for 24 hours. Thus, this circumstance is likely to generate residual images when the display is rewritten.
Generation of such residual images can be reduced, for example, by repeatedly performing display refreshing operations at short intervals, by applying a high voltage when rewriting is performed, or by applying a voltage for a long period of time when rewriting is performed. In addition, as a method for solving such problems, JP-A-2004-325489 discloses a method for applying a high-frequency voltage to a common electrode.
However, in a case where generation of residual images is reduced by applying a high voltage or applying a voltage for a long period of time when rewriting is performed, if a plurality of units of display having different rewrite intervals is provided in a display region of an electronic watch or the like, an unnecessary amount of voltage is consumed even for a unit of display, such as a minute display or a second display, which has a short rewrite interval and which is less likely to generate a residual image. In addition, if display refreshing operations are performed at the same interval for all the units of display, display refreshing operations are often performed unnecessarily for a unit of display, such as a month display or a date display, which has a long rewrite interval. Thus, increased electric power is consumed. In addition, if the method for applying a high-frequency voltage is adopted, a driving circuit becomes complicated, and power loss due to parasitic resistance of the wiring is increased.